Information storage devices are used to retrieve and/or store data in computers and other consumer electronics devices. A magnetic hard disk drive is an example of an information storage device that includes one or more heads that can both read and write, but other information storage devices also include heads—sometimes including heads that cannot write.
In a magnetic hard disk drive, the head comprises a body called a “slider” that carries a magnetic transducer on its trailing end. The magnetic transducer comprises a writer and a read element. The magnetic transducer's writer may be of a longitudinal or perpendicular design, and the read element of the magnetic transducer may be inductive or magnetoresistive. In a magnetic hard disk drive, the transducer is supported in proximity to the magnetic disk by a hydrodynamic air bearing. As the motor rotates the magnetic disk, the hydrodynamic air bearing is formed between an air bearing surface of the slider of the head, and a surface of the magnetic disk. The thickness of the air bearing at the location of the transducer is commonly referred to as “flying height.”
Magnetic hard disk drives are not the only type of information storage devices that have utilized air bearing sliders. For example, air bearing sliders have also been used in optical information storage devices to position a mirror and an objective lens for focusing laser light on the surface of disk media that is not necessarily magnetic.
The flying height is a parameter that affects the performance of an information storage device. Accordingly, the nominal flying height is typically chosen as a careful compromise between each extreme in a classic engineering “trade-off.” If the flying height is too high, the ability of the transducer to write and/or read information to/from the disk surface is degraded. Therefore, reductions in flying height can facilitate desirable increases in the areal density of data stored on a disk surface. However, the air bearing between the slider and the disk surface cannot be eliminated entirely because the air bearing serves to reduce friction and wear (between the slider and the disk surface) to an acceptable level. Excessive reduction in the nominal flying height degrades the tribological performance of the disk drive to the point where the disk drive's lifetime and reliability become unacceptable.
One way that a disk drive designer can improve the prospects of reaching an acceptable compromise in the “trade-off” described above, is to increase the complexity of the disk drive so as to dynamically control flying height. That is, additional head components and/or disk drive components that can function as a flying height actuator are included and actively controlled so that the flying height can be temporarily reduced only while the head is reading or writing. When the head is not reading or writing, it can “fly” at a slightly-higher nominal flying height to improve tribological performance. Such active control of flying height is sometimes referred to as “dynamic flying height” control (a.k.a. “DFH”).
The magnetic disk, mentioned above, includes various layers deposited during the manufacturing process. Generally, the disk includes a thin film magnetic layer and a protective carbon-based overcoat. The layers of the disk and process steps for manufacturing the disk are known in the art. During the disk manufacturing process it is possible for metal contamination to occur in the carbon overcoat. It has been found that when operating a hard drive having a contaminated disk, the head will pick up (i.e., become contaminated) with the metal particles resulting in reduced performance.
Thus, there is a need in the art for a method for testing a head for contamination when operating with a magnetic disk.